This invention relates to postage meters and in particular to the storage of data in postage meters.
Known postage meters are provided with electronic circuits to carry out accounting and control functions and printing means operated by the electronic circuits to print postage information on mail items. The electronic circuits include memories to store accounting data, the memories generally include a descending register to store a value of credit available for use in franking mail items, an ascending register for storing an accumulated value of postage charge used by the postage meter in franking mail items and an items register for storing a count of the number of mail items on which postage data has been printed by the postage meter in franking those items. The memories are non-volatile so that in the event of interruption of the supply of power to the postage meter, due for example to a fault or power down of the postage meter, the accounting data is retained and not lost.
In order to provide verifiable storage of the accounting data, it has been customary to provide a plurality of replications of the registers in the memories and for example usually two separate memory devices are provided and two of each register is provided in each memory device. Thus in the event of a fault occurring in one of the registers resulting in corruption of data stored in that register, the data can be ascertained from the other copies of that register. During operation of the postage meter in carrying out a franking operation, the accounting circuits check that the data content of all replications of each register are in agreement and, in the event that the data in any replication of a register is inconsistent with data in other replications of that register, the accounting circuits cause inhibition of use of the postage meter for franking operations. Continued use of the postage meter is possible only after examination and correction of the data by an authorized person.
It has also been proposed to provide a facility in or in association with postage meters for departmental accounting to enable maintenance of separate accounting records for each of a number of different departments or organizations using the same postage meter. For this purpose, a set of subsidiary registers is provided, one register for each department respectively, and in response to an input indicating a specific selected department the postage meter accounting circuits operate not only to generate and store accounting data for storage in the registers used by the postal authority for determination of credit available in the meter and expenditure of postage charge by the meter but also to generate and store data relating to use of the postage meter in franking mail items on behalf of the selected department.
It will be appreciated that the accounting data stored in those registers storing accounting data in respect of overall use of the postage meter is critical since payment by a user to a postal authority for postage charge dispensed by the meter is dependent upon that data. Any error in that data would result either in the postal authority losing revenue or the user paying a greater amount than the postage charge dispensed. However with departmental account records, any error in those departmental records does not result in incorrect payment between legal entities, i.e. a user company and the postal authority, but only inaccuracy in accounting between departments of a single legal entity. Accordingly it has been customary to treat departmental records as being noncritical.